U.S. patent application number 09/390100 was filed with the patent office on 2002-04-11 for resilient attachment materials for personal care products.
Invention is credited to MARTIN, TIMOTHY RAY, SCHMIDT, RICHARD JOHN.
Application Number | 20020042601 09/390100 |
Document ID | / |
Family ID | 26798906 |
Filed Date | 2002-04-11 |
United States Patent
Application |
20020042601 |
Kind Code |
A1 |
MARTIN, TIMOTHY RAY ; et
al. |
April 11, 2002 |
RESILIENT ATTACHMENT MATERIALS FOR PERSONAL CARE PRODUCTS
Abstract
There is provided a hook and loop attachment means made up of a
hook portion and a loop portion where the loop and/or the hook
portion is convex and is underlain by a resilient material or
hollow area. The hook and loop attachment means is useful in the
attachment of personal care products.
Inventors: |
MARTIN, TIMOTHY RAY;
(ALPHARETTA, GA) ; SCHMIDT, RICHARD JOHN;
(ROSWELL, GA) |
Correspondence
Address: |
JAMES B. ROBINSON
KIMBERLY-CLARK WORLDWIDE, INC.
401 NORTH LAKE STREET
NEENAH
WI
54956
|
Family ID: |
26798906 |
Appl. No.: |
09/390100 |
Filed: |
September 3, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60102025 |
Sep 28, 1998 |
|
|
|
Current U.S.
Class: |
604/391 ; 24/442;
604/387 |
Current CPC
Class: |
A44B 18/0069 20130101;
Y10T 24/27 20150115; A44B 18/0061 20130101 |
Class at
Publication: |
604/391 ;
604/387; 24/442 |
International
Class: |
A61F 013/15; A44B
001/04; A44B 011/25; A44B 017/00; A44B 018/00 |
Claims
What is claimed is:
1) A hook and loop attachment means comprising a hook portion and a
loop portion wherein at least one of said portions has at least one
convex portion.
2) The hook and loop attachment means of claim 1 wherein said
convex portion is underlain by a resilient material.
3) A hook and loop attachment means of claim 1 wherein said convex
portion is underlain by avoid.
4) The hook and loop attachment means of claim 1 wherein said
attachment means has a peak peel strength at least 20 percent
greater than an attachment means lacking a convex portion.
5) The hook and loop attachment means of claim 1 having two convex
portions.
6) A personal care product comprising the hook and loop attachment
means of claim 1.
7) The personal care product of claim 6 which is a diaper.
8) The personal care product of claim 6 which is a training
pant.
9) The personal care product of claim 6 which is an incontinence
product.
10) The personal care product of claim 6 which is a bandage.
11) The personal care product of claim 6 which is a feminine
hygiene product.
12) The hook and loop attachment means of claim 3 wherein said
hollow area is formed by pleating.
13) The hook and loop attachment means of claim 3 wherein said
attachment means has a peak peel strength at least 20 percent
greater than an attachment means lacking a convex portion.
14) The hook and loop attachment means of claim 3 having two convex
portions.
15) A personal care product comprising the hoop and loop attachment
means of claim 3.
16) The personal care product of claim 15 which is a diaper.
17) The personal care product of claim 15 which is a training
pant.
18) The personal care product of claim 15 which is an incontinence
product.
19) The personal care product of claim 15 which is a bandage.
20) The personal care product of claim 15 which is a feminine
hygiene product.
21) A personal care product comprising a hook and loop attachment
means wherein said attachment means has a peak peel strength at
least 20 percent greater, and a peak shear strength at least 50
percent greater, than an attachment means lacking a convex portion.
Description
[0001] This application claims priority from U.S. Provisional
Patent Application 60/102,025, filed Sep. 28, 1998.
FIELD OF THE INVENTION
[0002] The present invention relates to a structure in an article
for personal care like diapers, training pants, absorbent
underpants, adult incontinence products, swim wear, bandages and
feminine hygiene products.
BACKGROUND OF THE INVENTION
[0003] Personal care articles include such items as diapers,
training pants, feminine hygiene products such as sanitary napkins,
incontinence garments and devices, swim wear, bandages and the
like. The most basic design of such articles usually includes a
bodyside liner, an outercover and an absorbent core disposed
between the bodyside liner and the outercover.
[0004] Various attachment means have been used to keep the personal
care product in place on the wearer. Tape, hook and loop systems
and slip on garment designs requiring no separate attachment
devices, for example, have been used. Each of these means has its
own idiosyncratic deficiency, however. Tape, for example, will
sometimes not adhere properly if there is lotion or other
contaminants in the area of attachment, also known as the "landing
zone". Hook and loop fasteners sometimes fail due to lateral
forces, for example, and slip on designs cannot be easily opened
and closed to check for insults. There remains a need for an
attachment means, which is not easily affected by contaminants,
resists lateral forces well and which may be detached and
reattached easily a number of times.
[0005] It is an object of this invention, therefore, to provide an
attachment means which can be reattachably detached, is resistant
to contaminants in the landing zone, and which holds up well to
peel and shear forces. It is a further object of this invention to
provide personal care products incorporating such a superior
attachment means.
SUMMARY OF THE INVENTION
[0006] The objects of the invention are achieved by a hook and loop
attachment means, which is made up of a hook portion and a loop
portion where at least one of the portions is convex and is
underlain by a resilient material or hollow area. The hook and loop
attachment means is useful in the attachment of personal care
products.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a photograph of the convex hook component of this
invention showing individual hooks as well as the curvature of the
entire hook component.
[0008] FIG. 2 is a photograph showing the individual hooks of a
hook and loop fastener wherein the hooks face in different
directions.
[0009] FIG. 3 is a drawing of a typical personal care product, in
this case a diaper, showing the front, back and the hook and loop
components in their relative positions.
[0010] FIG. 4 shows a cross section view of a hook component
underlain by a resilient material which is in turn attached to, or
an integral part of, a backing material which may be a personal
care product.
[0011] FIG. 5 shows a variation of FIG. 4 wherein the resilient
underlaying material is absent and the hook component is folded in
such a manner as to cause it to rise out of the flat plane of the
backing.
[0012] FIG. 6 shows another variation of FIG. 4 wherein there are a
multiciplicities of convexities in the hook material. These may be
formed by placing an underlayment below the hooks or by
folding.
[0013] FIG. 7 is a picture showing a hollow underlayment, which may
be used in the practice of the invention, in a position of
attachment.
[0014] FIG. 8 is a picture showing a resilient underlayment, which
may be used in the practice of the invention, in a position of
attachment.
[0015] FIG. 9 is a picture showing a resilient underlayment, which
may be used in the practice of the invention, in a position wherein
the material is being peeled.
DEFINITIONS
[0016] "Disposable" includes being disposed of after use and not
intended to be washed and reused.
[0017] "Front" and "back" are used throughout this description to
designate relationships relative to the garment itself, rather than
to suggest any position the garment assumes when it is positioned
on a wearer.
[0018] "Layer" when used in the singular can have the dual meaning
of a single element or a plurality of elements.
[0019] By the term "similar hook" what is meant is a hook which
uses essentially the same hook as the inventive material but in
which the hook component is flat and not convex. According to
Webster's New Collegiate Dictionary (1980), "similar" means 1)
having characteristics in common; strictly comparable, 2) alike in
substance or essentials; corresponding. Using this commonly
accepted meaning of the word similar, this term means that all
other conditions are essentially the same except for the conditions
mentioned.
[0020] As used herein the term "polymer" generally includes but is
not limited to, homopolymers, copolymers, such as for example,
block, graft, random and alternating copolymers, terpolymers, etc.
and blends and modifications thereof. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible
geometrical configurations of the molecule. These configurations
include, but are not limited to isotactic, syndiotactic and random
symmetries.
[0021] As used herein the term "nonwoven fabric or web" means a web
having a structure of individual fibers or threads, which are
interlaid, but not in an identifiable manner as in a knitted
fabric. Nonwoven fabrics or webs have been formed from many
processes such as for example, meltblowing processes, spunbonding
processes, and bonded carded web processes. The basis weight of
nonwoven fabrics is usually expressed in ounces of material per
square yard (osy) or grams per square meter (gsm) and the fiber
diameters useful are usually expressed in microns. (Note that to
convert from osy to gsm, multiply osy by 33.91).
[0022] "Spunbonded fibers" refers to small diameter fibers that are
formed by extruding molten thermoplastic material as filaments from
a plurality of fine capillaries of a spinneret. Such a process is
disclosed in, for example, U.S. Pat. No. 4,340,563 to Appel et al.,
and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No.
3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394
to Kinney, U.S. Pat. No. 3,502,763 to Hartman, and U.S. Pat. No.
3,542,615 to Dobo et al. The fibers may also have shapes such as
those described in U.S. Pat. No. 5,277,976 to Hogle et al., U.S.
Pat. Nos. 5,466,410 to Hills and 5,069,970 and 5,057,368 to Largman
et al., which describe fibers with unconventional shapes.
[0023] "Conjugate fibers" refers to fibers which have been formed
from at least two polymers arranged in substantially constantly
positioned distinct zones across the cross-section of the fibers
and which extend continuously along the length of the fibers.
Conjugate fibers are taught in U.S. Pat. No. 5,108,820 to Kaneko et
al., U.S. Pat. No. 5,336,552 to Strack et al., and U.S. Pat. No.
5,382,400 to Pike et al.
[0024] "Bonded carded web" refers to webs that are made from staple
fibers which are sent through a combing or carding unit, which
separates or breaks apart and aligns the staple fibers in the
machine direction to form a generally machine direction-oriented
fibrous nonwoven web. Such fibers are usually purchased in bales,
which are placed in an opener/blender, or picker, which separates
the fibers prior to the carding unit. Once the web is formed, it
then is bonded by one or more of several known bonding methods. One
such bonding method is powder bonding, wherein a powdered adhesive
is distributed through the web and then activated, usually by
heating the web and adhesive with hot air.
[0025] "Personal care product" means diapers, training pants,
absorbent underpants, adult incontinence products, swimwear,
bandages and feminine hygiene products.
[0026] "Feminine hygiene products" means sanitary napkins or pads,
and panty-liners.
[0027] "Shear force" refers to forces acting generally parallel to
the plane of the substrate of the hook and loop fastening
system.
[0028] "Peel forces" refers to forces acting generally
perpendicular to the plane of the substrate of the hook and loop
fastening system.
TEST METHODS AND MATERIALS
[0029] Peel Test: The peel force value measures the force needed to
peel apart a hook and loop fastening system and can be determined
in accordance with standard procedure ASTM D5170, approved Sept.
15, 1991 and published November 1991; with the following
particulars. The loop material to be tested is cut into a
rectangle, 76 mm (3 inch) by 152 mm (6 inch) with the longer
dimension in the cross-machine direction. The loop material is
placed under the clamping plate of a rolldown machine. The hook
material is placed on top of the loop material and attached by the
rolldown machine using a 2 kg roller. A suitable rolldown machine
is part number HR-100 available from Chemsultants International, of
Mentor, Ohio. During the engagement of the fastener components, the
roller is rolled over the test specimen through one cycle in the
direction of the cross-wise "width" of the sample. In addition, the
initial peel by hand to "raise the loops" is omitted. After the
hook and loop are properly attached, the combination is placed in
the testing apparatus, an Instron Model 2712-004 tensile tester
with 102 mm (4 inch) rubberized grip faces (Instron Corporation,
Canton Mass. 02021). The hook base is inserted in the upper grip
and the loop in the lower in such a manner that the movement of the
grips away from each other will result in the peeling apart of the
two materials. Slack is removed and the machine is started. The
tester is set with a crosshead speed of 500 mm/min. and a gage
length of 76 mm. Measurements are begun at 10 mm and end at 46 mm
and are in grams. The reported value of a peel test result is a
peal load value employing MTS TESTWORKS software with a peak
criteria of 2%. Additionally, the peel force value is normalized to
be stated in terms of force per unit length of the "width"
dimension of the fastener component on the test specimen, such as
grams per inch or grams per centimeter. The MTS TESTWORKS software
is available from MTS Systems Corporation, a business having
offices in Eden Prairie, Minn.
[0030] Shear Test: The shear force value measures how well the hook
and loop stay engaged against in-plane shear force and can be
determined in accordance with the standard procedure ASTM D-5169,
approved Sep. 15, 1991 and published November 1991 with the
following particulars. The materials are prepared in the same
manner as in the peel test except that non-printed loop material
only is cut in to a size of 25 mm (1 inch) in the machine direction
by 152 mm (6 inch) in the cross machine direction. After the
rolldown machine has engaged the hook and loop materials to each
other as described above, they are removed and placed in the
Instron Model 2712-004 tensile tester, hooks in the upper grip,
loops in the lower in such a manner that the movement of the grips
away from each other will not result in the peeling apart of the
two materials. Slack is removed and the machine is started. The
tester is set with a crosshead speed of 500 mm/min. and a gage
length of 76 mm. Measurements are begun at 10 mm and end at 46 mm
and are in grams. The shear force value is normalized to be stated
in terms of force per unit area of the test specimen, such as
grams-force per inch.sup.2 (or gmf/cm.sup.2).
[0031] Material caliper (thickness): The caliper of a material is a
measure of thickness and is measured at 0.05 psi with a
Starret-type bulk tester, in units of millimeters.
[0032] Density: The density of the materials is calculated by
dividing the weight per unit area of a sample in grams per square
meter (gsm) by the bulk of the sample in millimeters (mm) at 68.9
Pascals and multiplying the result by 0.001 to convert the value to
grams per cubic centimeter (g/cc). A total of three samples would
be evaluated and averaged for the density values.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Personal care products include such items as diapers,
training pants, feminine hygiene products such as sanitary napkins,
panty-liners and tampons, incontinence garments and devices, swim
wear, bandages and the like. The most basic design of such articles
typically includes a bodyside liner, an outercover and an absorbent
core disposed between the bodyside liner and the outercover. Also
necessary is some sort of attachment means so that the product
stays in place. Optional layers include fluid transfer and
distribution layers.
[0034] The bodyside layer is sometimes referred to as a bodyside
liner or topsheet. In the thickness direction of the article, the
liner material is the layer against the wearer's skin and so the
first layer in contact with liquid or other exudate from the
wearer. The liner further serves to isolate the wearer's skin from
the liquids held in an absorbent structure and should be compliant,
soft feeling and non-irritating.
[0035] The bodyside liner can be surface treated with a selected
amount of surfactant or otherwise processed to impart the desired
level of wettability and hydrophilicity. If a surfactant is used,
it can be an internal additive or applied to the layer by any
conventional means, such as spraying, brush coating and the like,
prior to the deposition of the next layer.
[0036] The fluid retention or absorbent core layer must absorb
liquid from the adjacent bodyside layer in a controlled manner such
that liquid may be stored away from contact with the body.
Retention materials generally comprise binder, synthetic fibers and
natural fibers. While any of the layers of a personal care product
may optionally contain a superabsorbent, the fluid retention layer
is the most logical layer to contain such a component.
[0037] The garment side liner layer, also referred to as a
backsheet or outer cover is the farthest layer from the wearer. The
outer cover functions to prevent body exudates contained in an
absorbent structure from wetting or soiling the wearer's clothing,
bedding, or other materials contacting the personal care product.
The outer cover has traditionally been formed of a thin
thermoplastic film, such as polyethylene film, which is
substantially impermeable to liquid but may optionally be composed
of a vapor or gas permeable, microporous "breathable" material,
that is permeable to vapors or gas yet substantially impermeable to
liquid.
[0038] The optional fluid transfer layer, also referred to as a
surge layer, is most typically interposed between and in intimate,
liquid communicating contact with the bodyside liner and another
layer such as a fluid distribution or absorbent core layer. The
fluid transfer or surge layer allows fluid movement through itself
generally in the Z-direction, i.e. away from the bodyside and
towards the garment side.
[0039] An optional distribution layer may be interposed above
(toward a wearer) the fluid retention layer and must be capable of
moving fluid from the point of initial deposition to where storage
is desired. The fluid distribution layer, therefore, in addition to
allowing fluid movement through itself in the Z-direction, also
moves fluid in the X and Y directions. Distribution must take place
at an acceptable rate such that the target insult area, generally
the crotch area, is ready for the next insult. The time between
insults can range from just a few minutes to hours, generally
depending on the age of the wearer and the personal care product in
question.
[0040] The breathable outercover discussed above is an example of
the approach, which has been used previously to increase the
ability of air to enter the product. The breathable outercover
allows air through, and, in bench testing, can provide good air
flow rates as measured by conventional ASTM permeability testing.
While a breathable outercover will permit air to flow through, in
actual use there is no way to guarantee the flow of air through the
product and all the way to the skin, since this method is entirely
passive. The dynamic air flow provision remedies this by avoiding
the exclusive reliance on passive air entry and forcing or drawing
air into the product into the region between the skin and the
product.
[0041] Various attachment means have been used to keep the personal
care product in place on the wearer. Adhesive tape, mechanical
systems and slip-on garment designs requiring no separate
attachment devices, for example, have been used. Oils and powders
less easily contaminate attachment means such as mechanical
fastening systems than they contaminate adhesive tape fastening
systems. Additionally, mechanical fastening systems may be easily
reused. All of these features provide advantages when applied to a
disposable diaper intended for use on an infant, for example. Also,
a refastenable mechanical fastening system provides the advantage
the infant may be checked to see if soiling of the disposable
diaper has occurred during the wearing period.
[0042] Mechanical fastening systems typically employ two
components--a male (hook) component and a female (loop) component.
The hook component usually includes a plurality of semi-rigid,
hook-shaped elements anchored or connected to a base material. The
loop component generally includes a backing material from which a
plurality of upstanding loops project. The hook-shaped elements of
the hook component are designed to engage the loops of the loop
material, thereby forming mechanical bonds between the hook and
loop elements of the two components.
[0043] The loop component of the fastening system typically is
placed on the body of the garment and the hook component of the
fastening system is placed on a strap or "ear", which may be
elastic. For example, U.S. Pat. No. 5,664,302 describes hook and
loop fasteners wherein the loop material is underlain by a
substrate, which is a sheet of elastic material. Hook fastening
materials and methods of making such hook fastening materials are
disclosed in U.S. Pat. Nos. 5,326,415, 5,318,741, 5,230,851,
5,058,247 and 5,116,567. Examples of hooks for hook and loop
fasteners may also be found in U.S. Pat. No. 4,984,339, assigned to
Velcro Industries BV of the Netherlands. An example of a suitable
loop material may be found in U.S. Pat. No. 5,858,515 assigned to
Kimberly-Clark Worldwide, Inc.
[0044] FIG. 3 shows a typical personal care product, in this case a
disposable diaper 20, which has a front 21 and back 24. The front
21 has thereon a loop component 22 in the "landing area" or area of
attachment for the hook component 23 which is on an "ear" 25 which
is attached to, or an integral part of, the back 24. A "disposable
diaper" is a particular personal care product intended and scaled
to be worn by an infant. Incorporated by reference, some examples
of disposable diapers are described in U.S. Pat. No. 5,151,092,
U.S. Pat. No. 5,242,436 and U.S. Pat. No. 3,860,003, all of which
are hereby expressly incorporated by reference.
[0045] Hooks are desirably formed of a stiffer, resilient material
so that the wearer or caregiver can easily grasp the hook to
disengage the fastening system and so that the hooks will spring
open and recover without failure. This resiliency is what that
enables the hook to resume its curved configuration after being
bent as a result, for example, of the disengagement of the mating
interlocking materials.
[0046] The term resilient refers not only to the hook but also to
the backing material and the backing structure. The backing
material is that material to which the base of the hook is attached
and which is usually the same material from which the hook is
formed. The backing structure refers to the combination of the
backing material of the hook and/or loop and any underlying
material, as well as to its configuration.
[0047] Previous investigators have discovered that absorbent
articles including an interlocking fastening component having a
resilient, concave backing structure are well suited to maintain
proper attachment of the fastening system and such a system is
described in U.S. Pat. No. 5,722,968, incorporated herein by
reference in its entirety. This patent teaches that the edges and
corners of the resilient, contoured interlocking fastening
components do not project tangentially away from the body of the
wearer as is the case with conventional flat interlocking fastening
components and result in the edges and corners of the contoured
interlocking fastening components penetrating deeply into the
mating interlocking materials. This deep penetration ensures that
clothing or other materials passing over the garment fastening
system are less likely to snag on protruding edges and corners.
This is thought to be a particularly significant problem for small
individuals, where the angles of curvature of the body may be
greater than for less slim individuals.
[0048] The inventors have surprisingly found that a fastening
component shaped opposite to that taught in U.S. Pat. No.
5,722,968, i.e. one that is convex, provides superior resistance to
peel forces.
[0049] The convexity of the instant invention is clearly visible in
the photograph, which is FIG. 1, which in this case shows the
individual hooks and the clear curvature of the hook component.
FIG. 4 is a cross sectional view of a hook component 1 which is
convex and which is underlain by a resilient material 2 which is in
turn connected in some manner to a backing 3. The backing 3 may be,
for example, the ear as shown in FIG. 3. The embodiment having a
resilient material under the hooks may also be seen in FIG. 8 where
the hooks are attached to the loops on both sides of the resilient
material, and in FIG. 9 where the hook component is partially
unconnected from the loop component.
[0050] FIG. 5 shows a hook component 1 which is folded or pleated
in such a manner as to rise out of the flat surface of the backing
3 without the requirement of a resilient underlayment. In the
configuration of FIG. 5, a hollow or void area 4 underlies the hook
component 1. Another embodiment having a hollow or void area under
the hooks is visible in the photograph that is FIG. 7. FIG. 6 is a
variation of FIG. 4 wherein multiple convexities are formed in the
hook component 1 over an underlayment 5 which may be a resilient
material or hollow, in the same manner as single convexities are
formed.
[0051] As noted previously, the hook component may be placed on the
ears, straps or body of a personal care product. The loops,
therefore, may also be on either the ears, straps or body of the
personal care product. In an alternative embodiment, the loops may
be underlain by a resilient material in a manner similar to that
shown in FIG. 4, for example, while the hooks may be underlain by a
relatively flat material. The loop material may also alternatively
be pleated so that multiple convexities are formed and so the loops
are underlain by void or hollow areas in a similar manner to that
shown in FIG. 5. The stiffness of the loops may be controlled by
the amplitude and frequency of the pleats.
[0052] The ability of the resilient interlocking fastening
component to retain its configuration can be enhanced by
controlling the construction of the backing structure. The backing
structure of the interlocking fastening component is desirably
formed of a construction or a material that has sufficient memory
characteristics such that the backing structure will return
approximately to a its original configuration after repeated
engagement and disengagement cycles with a complementary fastening
component. Because the resilient interlocking fastening components
are desirably incorporated on attachment straps or ears, the
resilient interlocking fastening components should maintain their
curvature in order to remain effective during use. For reasons of
comfort and performance, the absorbent articles are generally
constructed of flexible components so that they conform to the body
of the wearer. Additionally, the loop of the fastening system,
which either forms an integral part of the garment or is a separate
element attached to the garment, desirably comprises a generally
flexible material. Consequently, the loop tends to conform to the
shape of the wearer and enhance comfort, however, this invention is
not meant to be limited to embodiments in which only the loop
material is that which is nearest the body of a wearer.
[0053] The hook component, comprising many individual hooks or
"prongs", may have such individual hooks aligned in various
direction, i.e. there is no prohibition against hooks facing in
different directions. FIG. 2, in fact, shows hooks pointed in two
directions. The individual hooks can be arranged in the machine
direction, the cross direction, or any angle between the two. While
the theoretical arrangement of individual hooks is almost infinite,
practically they are made in only a small number of ways; all in
one direction or half in each of two directions. It should be noted
that these particularities of individual hook placement are
dependent on the end use and objective of the investigator and all
cannot possibly be recited here. They are, however, within the
understanding and ability of those skilled in the art without undue
experimentation. The instant invention effects hook configuration
because the movement of the resilient backing structure results in
the movement of the hooks toward and away from each other as the
resilient backing structure responds to the movement of the wearer
and the shear forces on the personal care product.
[0054] In order to determine the amount of increase in the strength
due to the instant invention, various configurations were tested
according to the peel and shear tests described in the Test Methods
section above. These configurations were (1) a flat, control; (2) a
round sponge rubber core; (3) a "D" shaped sponge rubber core; and
(4) a double "D" shaped sponge rubber core. The results are given
in the Table below.
1TABLE Material Peak load peel, gm/2 inch width Peak load shear,
gm/in.sup.2 1 445 2115 2 566 2388 3 575 3025 4 546 3384
[0055] The inventors have found, as can been seen from the results
in the Table, that a hook and loop fastener in which at least one
component is convex with a resilient material or hollow area
underlaying it has at least a 20 percent superior peel strength to
that of a similar hook material without a resilient material or
hollow underlayment. In addition, the shear strength is also
superior and could be 50 percent greater or more. The values in the
Table also indicate that a more resilient material, like numbers 3
and 4, give a greater increase in shear strength than a relatively
less resilient material such as that of number 2. The strength of
hook and loop systems according to the invention is also superior
to that of mechanical fasteners using concave hook fasteners. The
inventors believe that the source of such superiority must be the
rounded orientation of the hook and loop fastener material. Its
believed that when the hook and loop fastening system is placed
under peel forces, the components engage each other even more
strongly as one component rolls upward in response to the
imposition of the peeling force.
[0056] The peel and shear forces peak during testing as the
materials are pulled apart. After the peak, the tensile force need
to pull the pieces apart falls off, eventually to zero when the
pieces are completely separated. In embodiments with more than one
convexity, however, the force tends to fall after a peak
corresponding to the first convexity and then rise for the second
convexity, again reaching a peak and falling off. Placing a
multiplicity of convexities under a component of the hook and loop
system results in a multiplicity of peaks in the force needed to
pull the materials apart. Appropriately sizing and spacing these
convexities can result in a more uniform force need to separate the
portions since the valleys between the peaks can be minimized.
[0057] As will be appreciated by those skilled in the art, changes
and variations to the invention are considered to be within the
ability of those skilled in the art. Such changes and variations
are intended by the inventors to be within the scope of the
invention.
[0058] It should further be noted that any patents, applications or
publications referred to herein are incorporated by reference in
their entirety.
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